Ball and socket joints are important mechanical components, because they allow three degrees of freedom. Only joysticks and vehicle components shall be mentioned here as examples of two typical applications of ball and socket joints. However, the measurement of the rotation and tilt angles has been an essential problem for the use of ball and socket joints so far. A great variety of rotation angle sensors have been known for the measurement of the rotation angle. They use mostly a stationary magnetic field, in which a sensor is arranged, whose resistance changes as a function of the rotary movement of the ball and socket joint. The drawback of these sensors is that they determine exclusively the rotary movement and do not detect the tilting movement of the ball and socket joint. If the tilting movement is to be detected as well, a complicated coupling of a plurality of sensors is disadvantageously necessary.
Thus, a measuring means with a magnetoresistive sensor for the contactless, continuous measurement of the change in the position of a motor vehicle body, in which a permanent magnet is arranged in the upper apex of a ball head of a ball and socket joint and the sensor is arranged in the area below the apex of the opening of the ball and socket joint socket, is known from the European Patent EP 0 617 260 B1.
Sensors operating on the basis of Hall sensors disadvantageously have a high sensitivity to external magnetic fields and temperature changes. It is also disadvantageous in case of the use of Hall sensors that the aging of the exciting magnets is not compensated. Furthermore, the calculation of the rotation and tilt angles is very complicated, and it is necessary to record a characteristic diagram in most cases.